Space is a much different atmosphere than life on Earth's surface. In space, you are constantly subject to 0-gravity which consequently makes your bones and muscles become gradually weaker as they are not being frequently used. This is why it is so important for astronauts to exercise. On the other hand, life in a desk job is not particularly healthy either. They are similar because you are also not using your muscles and bones to accomplish many tasks. However, they are different because in a desk job, you are still subject to gravity and do have to work harder to stay upright. This is why many of us have bad posture. Space is also different than a desk job because you are constantly moving around, even if it is easier for your muscles.
